Figure 9. Conversion of GMAb Concentration Data into International units.
A. Comparison of Serum GMAb concentration Determined with the PCRS and MCRS. Separate sets of standard dilutions (1:100, 1:3000, 1:6000, 1:12000) were prepared from serum from 14 autoimmune PAP patients and 1 healthy person. All standard dilutions (60 total) were used to measure GMAb concentration with the PCRS ([GMAb]PCRS) and MCRS ([GMAb]MCRS) as described in the legends to Figures 3 and 7, respectively, in parallel on the same plate. All in-range values (n = 41; defined in the legend to Figure 5) are shown and were used for analysis. The relationship between GMAb concentration determined using each of the two reference standards was evaluated by linear, quadratic (not shown to improve readability), or cubic regression analysis. The correlation coefficients for regression analysis were 0.980 (linear), 0.998 (quadratic), and 1.00 (cubic).
B. Effect of Regression Method and GMAb Concentration Range on the Accuracy of Conversion of [GMAb]PCRS to International Units. Using the data and regression equation parameters determined from the linear, quadric, or cubic regression analysis described above (panel A), the values for GMAb concentration determined with the PCRS ([GMAb]PCRS) were converted mathematically to values that would have been obtained if the MCRS had been used (i.e., equivalent to [GMAb]MCRS). The percent error of the [GMAb]PCRS measurement was calculated as [GMAb]PCRS minus [GMAb]MCRS divided by [GMAb]MCRS multiplied by 100; where [GMAb]PCRS are the unconverted values (None) or values after conversion using the linear, quadratic, or cubic regression equation parameters (indicated) and [GMAb]MCRS is the value actually determined using the MCRS (assumed to be the true value). The dashed line represents a percent error of zero.
C. Determining the Equation to Convert [GMAb]PCRS Data to International units. Data from six independent experiments similar to and including the one shown in panel A were combined and cubic regression analysis was done to determine the equation needed to convert data for GMAb concentration determined using the PCRS into units equivalent to that determined using the MCRS. In total, serum samples from 55 autoimmune PAP patients and 12 healthy controls were used for determining the equation. The correlation coefficient (R2) was 0.98343.